Vulnerability · Published Sep 18, 2026 · Assigned by VulnCheck

CVE-2026-93750http-cache-semantics through 4.2.0 Cross-Client Cache Disclosure via Vary Wildcard

Medium 5.9

In plain English

A medium-severity security flaw in http-cache-semantics from kornelski. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 39% of all known vulnerabilities).

Severity (CVSS 3.1)5.9Medium

Exploit odds (30 days)0.4%top 61.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

http-cache-semantics through 4.2.0 contains a cache validation vulnerability in the _varyMatches() function that fails to properly validate Vary header wildcards due to byte-for-byte string comparison. Attackers can request URLs previously fetched by other clients to receive cached responses intended for different users, disclosing sensitive information across clients.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	node-got	no fix listed	DEBIAN-CVE-2026-93750
Debian:13	node-got	no fix listed	DEBIAN-CVE-2026-93750
Debian:14	node-got	no fix listed	DEBIAN-CVE-2026-93750
Ubuntu:22.04:LTS	node-got	no fix listed	UBUNTU-CVE-2026-93750
Ubuntu:24.04:LTS	node-got	no fix listed	UBUNTU-CVE-2026-93750
Ubuntu:26.04:LTS	node-got	no fix listed	UBUNTU-CVE-2026-93750
Ubuntu:26.10	node-got	no fix listed	UBUNTU-CVE-2026-93750

Affected products (as reported)

Vendor	Product	Versions
kornelski	http-cache-semantics	0 – through 4.2.0

Weakness: CWE-436 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

References

GitHub Issue #57 issue-tracking
https://github.com/kornelski/http-cache-semantics product
_varyMatches() exact-string wildcard test and unguarded per-field comparison technical-description
VulnCheck Advisory: http-cache-semantics through 4.2.0 Cross-Client Cache Disclosure via Vary Wildcard third-party-advisory